1. Field of the Invention
The present invention relates to an engine mount and a power unit vibration damping support structure which gives vibration damping support to a power unit on a vehicle body, and particularly to an engine mount and a power unit vibration damping support structure of a suitable and novel structure that gives vibration damping support to a transverse engine type power unit on a vehicle body at four points: front, rear, left, and right.
2. Description of the Related Art
With automobiles, in order to give stable support while reducing vibration transmission to the vehicle body, a power unit integrally constituted with an engine, transmission unit and the like has vibration damping support on the vehicle body at a plurality of locations via an engine mount. In particular, as one type of power unit support structure for a transverse engine type with the crank shaft arranged in the vehicle horizontal direction, from the past, there have been proposals for structures that give vibration damping support to the power unit on the vehicle body via respective engine mounts at four points including front, rear, left and right of the vehicle, as noted for example in Japanese Unexamined Patent Publication No. JP-A-2001-097050.
With this conventional four point support structure, as shown in FIG. 9, typically, a power unit 2 is made to have vibration damping support in relation to a sub frame 4 as the vehicle body comprising a front side member, front cross member and the like with a total of four engine mounts including the mounts LhMt and RhMt arranged at the left and right sides of the vehicle, and the mounts FrMt and RrMt arranged at the front and rear sides of the vehicle. Then, with a total of three mounts including the mounts LhMt and RhMt at the left and right sides and the mount RrMt at one of the front/rear sides arranged surrounding the center of gravity C.G. of the power unit 2, the static load of the power unit 2 is given distributed support, and torque roll reaction force or the like is received by the mount FrMt at the other of the front/rear sides.
Meanwhile, with this kind of four point support structure for a power unit, each engine mount needs to be arranged in a limited space, and particularly, the mounting space for the engine mounts LhMt and RhMt mounted at the left and right sides are unavoidably restricted depending on the vehicle width dimensions. Moreover, among these, taking into consideration the tilt of the principal axis of inertia, the engine mount LhMt mounted at the transmission 6 side in one of the left-right sides is mounted lower than the engine mount RhMt mounted on the engine 8 side in the other of the left-right sides, so that the mounting space is even more restricted. Therefore, with the engine mount LhMt mounted on the transmission 6 side in one of the left-right sides, there is a great deal of demand for more compact size.
However, when that engine mount LhMt is made more compact, due to things such as the volume of the rubber elastic body constituting the engine mount becoming smaller, there was a problem that it became difficult to realize both the required durability and low spring characteristics.